Brake cylinder



Aug. 2l, 1928,.

l c. c. FARMER .BRAKE CYLINDER Filed March 25, 1927 INVENTOR .CLYDE c. FARMER.

BY ATTORNEY Patented hug. 21, 1928.

\ unifi' gppism'rias, iBATiiNT) OFFICE.

renvian c. FARMER, orgrigiirsiinnen, erinnsvLvAnIA,1 Assienon 'ro THE wzis'riNG- HOUSE Ain BRAKE` COMPANY; or'jwiiiiyinnnrne, PENNSYLVANIA; A conronA- ation or PENNsYLvAniA'.,

'Application sieri: Marcin 25,f1i92'z,t @smal No; 173,307- l j' This inve'ntion rela-tes to' fluid pressure motor devices, and more particularly to la cylinderl and piston construction of the type employed as brake cylindersin {iuid pressure brake systems.

4ln cases where the cylinder and piston constri'iction is mounted in a' vertical position, as when on dump cars,

in* is liable to find its way. into the cylinder,

and it the' usual leather or composition piston packing. ring isA employed, the packing ring is subjected to excessive wear, as ivell as the' cylinder-walls. In addition, packing rings ot' leather or composition materialdo not stand up welltfunder high temperatures, to which the cylinders are sometimes subjected.` ,irl

The principal object of` my invention is to provide means for overcon'iingvthe above ditliculties. v In the accompanying drawing, the single figure is a 'sectional view of a. fluid pressure cylinder and piston construction embodying my invention. t

As shown in the drawing, the motor device comprises a cylinder 1, having a piston chamber 2 containing a provided with a pressure head 4 at one end, having an opening connected to a pipe 5 through which plied to and released from the cylinder. To the other end ot the cylinder is secured a non-pressure head 7. n

A hollow piston rod 6 is centrally secured to the piston 3 and slidably extends through a bore in the closed endof the cylinder non-pressure head 7. i v

In order to prevent dirt andforeign matter from entering the cylinder,vr I provide a shield 9, preferably cup-shaped, to the central portion ot the end face of which is secured a ring 8, by brazing or otherwise. Said ring is interiorly threaded and is e adapted to have' screw-threaded engagement with the outer end of the hollow piston rod 6. The shield 9 is of sufficient diameter to permit the non-pressure head to project into same, when the piston 3 is in the release position, as shown iii the drawing.; but is not permitted to engage the non-pressure head, when the piston 3 strikes the pressure head 4:. After adjusting the position of the l shield 9 and ring 8 on the piston rod 6, the

employed as a motor device v dirt or other `foreign matter t piston 3, and is fluid under pressure is' sup-v riiig is secured against` further movement by a rivet 15 through the ring -S'and piston rod 6. Y i," ,i

i A push'rod 1() is provided inside .the hollow piston rodl and has formed at its outer endjfa yokepbetweenthe armsfof which an operatinglever (not shown)f`is secured.

An opening is provided in the wall of the non-pressure head 7 and held in said opening vis anair strainer 14, comprising two perforated plates forming `an intermediate chamber, which is ,filled with .pulled curled hair, thestrainer bein0r secured to the wall of the ncnpressure head by screws 16;

' The 'piston y3 is formed with twoperiph` y eral grooves, each containing a piston ring 17 engaging the inner wall of `the cylinder 2 anden Athe hack ,of the piston is formed an annu-lar groove 18, in which one end of the usualv piston return spring 19 seats. The opposite end of the spring 19 seats` against the inside wallof the closed endet the non-` pressure head 7.y f j On the back of the piston 3, adjacent the annular groove 18, is a chaint'ered surface 20 adapted to engage the arcuate surface 21 fot the non-pressure head 7, when the piston 3 isV in application position.

In operation, fluid under pressure is supplied through pipe 5 to the face of the piston 3, thereby shitting the piston, piston rod 6 and push rod lOrupwardly against the pressure of the spring 19. This upward movement of the piston 3 tends to compress the fluid at atmospheric pressure back of the piston, but due to the atmospheric connection through the strainer let, the fluid i back ol' the piston is ejected into the atmosphere, thereby maintaining substantially at niospheric pressure in the spring chamber back of the piston.

A VIn order to prevent the piston rings 17 from becoming inoperative by being jammed v in their groovesby the impact of t-he piston 3 striking the non-pressure head 7, the eliainfered surface 2() on the back of the piston is adapted to engage the curved. surface 21 on the non-pressure head, on a line of less diameter than the diameter at the bottom of the ring grooves, so that the full force of the impact is received by the piston back of the ring grooves, where the full thickness of the piston is present.

Then the fluidundei pressure acting on the piston 3 lis vented to the atmosphere through pipe 5 to some low degree, the pressure of the spring 19 starts to move the piston and piston rod downwardly.

Vhen the piston .moves towards its nor mai release position, as shown inthe drawing, the pressure in the spring chamber back of the piston tends to be redueed below that of the atmosphere but is substantially maintained at atmospheric` pressure byy the ioiv of iiuid from the atmosphere through the strainer 14C. The strainer 14 thus pre-A vents any Vdirt or foreignmatter from enter ing the cylinder.

It will be noted thatl the shield 9 moves with the hollow pistoni rod 6, butin both extreme positions of the piston, the shield 9 prevents falling or shifting dirt or forf eign matter from coming in contact with the piston rod 6 and then being drawn into the interior of the non-pressure head through the clearance existing between the end of said piston rod and an air strainer disposed in an opening in said non-pressure head, 'said strainer being covered by said shield Whenr the piston is retracted.

2. TheV combinationwith a 'cylinder having La non-pressure head, affluid pressure controlled piston in said cylinder, and a piston vrc doonneete :l to said piston and extending through an opening in said non-pressure head, of an linteriorly threaded ring and a ycup-shaped dirt shield secured to said ring,

said .ring having screw-threaded engagement with the outer end ofsaid piston rod.,

f 3. The oombinationwith a iiuid pressure.

cylinder having anon-pressure head provided With an annular arcuate face, voil ar piston in said rcylinder provided With grooves for pistony rings and having a ehamfered inner face f adapted to engage said arcuate face; j. n

The combination with a Huid pressure ycylinder having anon-pressure head pro-- vided. with an kannulark arcuate faee,iof ra piston in said cylinder provided with grooves for piston rings and having a ehamfered inner l face adapted to engage saidy arcuatel face, the yline of contactbeing such that the force of impact is transmitted through they solid metal of the piston at the rear of thegrooves. I f yInftestimony whereof I my hand.

have hereunto set e i GLYDE o. FARMER. 

